Semiconductor device and method of manufacturing the same

Abstract

To obtain a semiconductor device capable of improving reliability and a manufacturing method thereof. An insulating substrate (1) has a circuit pattern (4). A semiconductor element (8) is mounted on the insulating substrate (1) and electrically connected to the circuit pattern (4). A housing (11) houses the insulating substrate (1) and the semiconductor element (8). An electrode (12) is provided to the housing (11). A front end surface of the electrode (12) is joined to the circuit pattern (4) by solder (14). The electrode (12) is pressure-bonded to the circuit pattern (4) by the housing (11). A protrusion (12d) is provided to the front end surface.

Description

TECHNICAL FIELD

[0001] The present application relates to a semiconductor device and a manufacturing method thereof. BACKGROUND

[0002] A semiconductor device in which electrodes mounted to a housing are soldered to a circuit pattern of an insulating substrate is disclosed (see Patent Document 1, for example).

[0003] Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2006-295158

[0004] When temperature cycles, warping occurs in the semiconductor device due to a difference in linear expansion coefficient of structural members. Due to this, the position of the electrode in the up-down direction with respect to the housing and the insulating substrate changes, and thus, a tensile stress or a compressive stress acts on the soldered portion of the electrode in the up-down direction. Since the insulating substrate is present, the electrode is difficult to displace in the compressive direction. However, the electrode is easy to displace in the tensile direction, and thus, there is a problem in that the solder deteriorates and peeling occurs, and the reliability decreases. SUMMARY

[0005] The present application has been made to solve the above-described problems, and has an object to provide a semiconductor device and a manufacturing method thereof capable of improving reliability.

[0006] The semiconductor device according to the present application is characterized by comprising: an insulating substrate having a circuit pattern; a semiconductor element mounted on the insulating substrate and electrically connected to the circuit pattern; a housing that houses the insulating substrate and the semiconductor element; and

[0007] an electrode provided to the housing, a front end surface of the electrode being soldered to the circuit pattern, the electrode being crimped to the circuit pattern by the housing, a protrusion being provided to the front end surface.

[0008] EFFECT OF THE INVENTION

[0009] In the present application, the electrode is crimped to the circuit pattern by the housing. Due to this, a tensile stress generated at the joint of the electrode and the circuit pattern due to warping at the time of temperature cycles can be reduced. In addition, the thickness of the solder is reduced due to the crimping, but the thickness of the solder can be ensured by providing the protrusion to the front end surface. Thus, peeling of the solder at the time of temperature cycles can be prevented, and the reliability can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a cross-sectional view showing a semiconductor device according to Embodiment 1.

[0011] Figure 2 is an enlarged cross-sectional view along line Figure 1 I-II.

[0012] Figure 3 This is a diagram illustrating the manufacturing process of the semiconductor device according to Embodiment 1.

[0013] Figure 4 This is a diagram illustrating the manufacturing process of the semiconductor device according to Embodiment 1.

[0014] Figure 5 This is an enlarged cross-sectional view of a portion of the semiconductor device according to Embodiment 1.

[0015] Figure 6 This is a cross-sectional view showing the semiconductor device involved in Embodiment 2.

[0016] Figure 7 This is a cross-sectional view showing a modified example of the semiconductor device according to Embodiment 2.

[0017] Figure 8 This is a top view showing a modified example of the semiconductor device according to Embodiment 2.

[0018] Figure 9 This is a cross-sectional view of the semiconductor device involved in Embodiment 3.

[0019] Figure 10 This is a cross-sectional view of the semiconductor device involved in Embodiment 4.

[0020] Figure 11 It is along Figure 10 Enlarged sectional view of I-II.

[0021] Figure 12 This is a cross-sectional view of the semiconductor device involved in Embodiment 5.

[0022] Figure 13 This is a side view showing the erected portion of the electrode according to Embodiment 6.

[0023] Figure 14 This is a side view showing a modified example 1 of the standing portion of the electrode according to embodiment 6.

[0024] Figure 15 This is a side view showing a modified example 2 of the standing portion of the electrode according to embodiment 6. Detailed Implementation

[0025] Referring to the accompanying drawings, the semiconductor device and its manufacturing method according to the embodiments are described. The same or corresponding structural elements are labeled with the same reference numerals, and sometimes repeated descriptions are omitted.

[0026] Implementation method 1.

[0027] Figure 1is a sectional view showing a semiconductor device according to Embodiment 1. The insulating substrate 1 has an insulating board 2, a metal pattern 3 on the lower surface of the insulating board 2, and circuit patterns 4, 5 on the upper surface of the insulating board 2. The insulating board 2 is ceramic such as AlN or SiN, or resin insulating.

[0028] The metal pattern 3 of the insulating substrate 1 is joined to the upper surface of the base board 6 by solder 6. The semiconductor element 8 is mounted on the insulating substrate 1. The lower surface electrode of the semiconductor element 8 is electrically connected to the circuit pattern 4 by solder 9. Note that the joining method is not limited to soldering, and can be Ag joining or laser welding, etc. The upper surface electrode of the semiconductor element 8 is electrically connected to the circuit pattern 5 by wiring 10 such as a wire. The housing 11 houses the insulating substrate 1 and the semiconductor element 8. The housing 11 is adhered to the upper surface of the base board 6.

[0029] The electrodes 12, 13 are mounted on the housing 11. The front end surface of the electrode 12 is joined to the circuit pattern 4 by solder 14. The electrodes 12, 13 are plate-shaped, and have a front end surface, main surfaces opposite to each other, and side surfaces opposite to each other. The front end surface is rectangular, and the short side of the front end surface corresponds to the thickness of the electrode 12, and the long side of the front end surface corresponds to the lateral width of the electrode 12.

[0030] The encapsulating material 15 encapsulates the insulating substrate 1, the semiconductor element 8, and the electrode 12, and electrically insulates the semiconductor element 8, etc. from the outside. The encapsulating material 15 is, for example, a gel, and preferably a resin such as a direct potting resin. The displacement of the electrode 12 at the time of temperature cycling is suppressed by the resin, and thus the reliability of the soldering is improved.

[0031] The electrode 12 has a fixed portion 12a embedded and fixed to the housing 11, a standing portion 12b standing above the circuit pattern 4, and a connecting portion 12c connecting the fixed portion 12a and the upper end of the standing portion 12b. The height of the upper end of the standing portion 12b of the electrode 12 is higher than the height of the fixed portion 12a. The fixed portion 12a is parallel to the upper surface of the base board 6 and the circuit patterns 4, 5 of the insulating substrate 1. On the other hand, the connecting portion 12c, which is led into the internal space of the housing 11, rises from the fixed portion 12a toward the upper end of the standing portion 12b, and is inclined with respect to the upper surface of the base board 6 and the circuit patterns 4, 5 of the insulating substrate 1. Due to this structure, the electrode 12 is crimped to the circuit pattern 4 by the housing 11. Similarly to the electrode 12, the front end surface of the electrode 13 is soldered to the circuit pattern 5, and the electrode 13 is crimped to the circuit pattern 5 by the housing 11.

[0032] Figure 2 is a sectional view taken along Figure 1An enlarged sectional view of I-II. A protrusion 12d is provided on the front end surface. By press-contacting the protrusion 12d of the electrode 12, a slight indentation is formed on the surface of the circuit pattern 4. Similarly to the electrode 12, a protrusion (not shown) is provided on the front end surface of the electrode 13.

[0033] Next, a manufacturing method of the semiconductor device according to the present embodiment will be described. Figure 3 and Figure 4 is a view showing a manufacturing step of the semiconductor device according to Embodiment 1. First, the semiconductor element 8 is mounted on the insulating substrate 1 to be electrically connected to the circuit pattern 4 of the insulating substrate 1. Next, the case 11 is mounted on the upper surface of the base plate 6 in a manner of housing the insulating substrate 1 and the semiconductor element 8. At this time, the electrode 12 is press-contacted to the circuit pattern 4 by the case 11. Further, the front end surface of the electrode 12 is soldered to the circuit pattern 4.

[0034] Before the case 11 is mounted, as shown in Figure 3 , the fixed portion 12a and the connecting portion 12c of the electrode 12 are linear, and the height of the upper end of the standing portion 12b of the electrode 12 is the same as that of the fixed portion 12a. After the case 11 is mounted, as shown in Figure 4 , the height of the upper end of the standing portion 12b of the electrode 12 is higher than that of the fixed portion 12a. In this way, the electrode 12 is deformed, and thus the electrode 12 is press-contacted to the circuit pattern 4.

[0035] In the present embodiment, the electrode 12 is press-contacted to the circuit pattern 4 by the case 11. Thus, the tensile stress generated at the joint of the electrode 12 and the circuit pattern 4 due to warping at the time of temperature cycle can be reduced. Further, the thickness of the solder 14 is reduced by the press-contacting, but the thickness of the solder 14 can be ensured by providing the protrusion 12d on the front end surface. Therefore, the peeling of the solder at the time of temperature cycle can be prevented, and the reliability can be improved.

[0036] Further, the presence of the solder 14 on the outer peripheral portion of the front end surface where the stress becomes large can alleviate the stress. Therefore, it is preferable that the protrusion 12d is not provided on the outer peripheral portion of the front end surface. Further, it is preferable that the protrusion 12d is two or more in order to uniformly maintain the thickness of the solder 14. Thus, the reliability of the soldering is improved.

[0037] Further, the front end surface of the standing portion 12b of the electrode 12, not the flat surface of the electrode 12 which is not plate-shaped, is jointed to the circuit pattern 4. Thus, the joint area of the electrode 12 is reduced. Therefore, in the case where the semiconductor element 8 or the wiring 10 is jointed to the circuit pattern 4 to which the electrode 12 is jointed, the space in which they are jointed is increased. Further, the current capacity can also be increased.

[0038] Figure 5is an enlarged sectional view of a part of the semiconductor device according to Embodiment 1. The distance R from the junction of the electrode 12 and the circuit pattern 4 to the end of the circuit pattern 4, the semiconductor element 8, or the external wiring 10 is greater than or equal to the height L of the solder 14 (R > L). Thus, the nodule of the solder 14 becomes a gentle shape with an angle of less than 45°, and the stress to the solder 14 is reduced, and thus the reliability of the soldering is improved.

[0039] Embodiment 2.

[0040] Figure 6 is a sectional view showing the semiconductor device according to Embodiment 2. The housing 11 has a square frame, i.e., an outer wall 11a, which surrounds the insulating substrate 1 and the semiconductor element 8, and a protruding portion 11b which protrudes from the outer wall 11a to the inner side of the outer wall 11a. The connecting portion 12c of the electrode 12 which is led to the inner side of the outer wall 11a is displaced upward, but is pressed down by contacting the lower surface of the protruding portion 11b. Thus, the electrode 12 is subjected to a force to be press-bonded to the circuit pattern 4. Thus, as in Embodiment 1, the tensile stress which occurs at the junction of the electrode 12 and the circuit pattern 4 due to warping at the time of temperature cycling can be reduced.

[0041] Figure 7 is a sectional view showing a modification of the semiconductor device according to Embodiment 2. Figure 8 is a plan view showing a modification of the semiconductor device according to Embodiment 2. The protruding portion 11b becomes a beam which spans the outer walls 11a of the housing 11 which face each other. In this case, the above-described effects are also obtained.

[0042] Embodiment 3.

[0043] Figure 9 is a sectional view showing the semiconductor device according to Embodiment 3. The housing 11 is directly adhered and fixed to the insulating substrate 1. The other structures are the same as in Embodiment 1. In this case, the electrodes 12, 13 are also press-bonded to the circuit patterns 4, 5 by the housing 11, and the same effects as in Embodiment 1 can be obtained.

[0044] Embodiment 4.

[0045] Figure 10 is a sectional view showing the semiconductor device according to Embodiment 4. Figure 11 is an enlarged sectional view along Figure 10 I-II. The circuit pattern 4 is provided with a recess 16. The recess 16 does not need to reach the insulating substrate 2 by penetrating the circuit pattern 4. The protrusion 12d is fitted in the recess 16. Thus, the junction area of the circuit pattern 4 and the solder 14 is increased, and thus the reliability of the junction is improved.

[0046] Embodiment 5.

[0047] Figure 12 is a sectional view showing a semiconductor device to which Embodiment 5 is applied. The other electrode 17 is arranged in parallel with the electrode 12. If two electrodes 12, 17, whose current flow directions are opposite, are arranged in close proximity in parallel, the magnetic fields cancel each other, and thus the inductance can be reduced. In addition, in the case where the two electrodes 12, 17 are at the same potential, the electrode density can be increased, and thus the current-carrying capacity is improved.

[0048] Embodiment 6.

[0049] Figure 13 is a side view showing a standing portion of an electrode to which Embodiment 6 is applied. A cutout 12e is provided on the side surface of the standing portion 12b of the electrode 12. Due to the cutout 12e, the rigidity of the electrode 12 is reduced. Thus, the stress to the solder 14 caused by the deformation of the electrode 12 is reduced, and thus the reliability of the soldering is improved.

[0050] Figure 14 is a side view showing a deformation example 1 of a standing portion of an electrode to which Embodiment 6 is applied. In Figure 13 , the cutout 12e is provided on both sides of the standing portion 12b, but in Figure 14 , it is provided on only one side. In this case, the same effect can be obtained.

[0051] Figure 15 is a side view showing a deformation example 2 of a standing portion of an electrode to which Embodiment 6 is applied. The cutout 12e is provided in the thickness direction, and the thickness of the standing portion 12b of the electrode 12 is partially thinned. Due to the thin portion, the rigidity of the electrode 12 is reduced. Thus, the stress to the solder 14 caused by the deformation of the electrode 12 is reduced, and thus the reliability of the soldering is improved.

[0052] Further, the semiconductor element 8 is not limited to being formed of silicon, and can be formed of a wide bandgap semiconductor having a larger bandgap than silicon. The wide bandgap semiconductor is, for example, silicon carbide, a gallium nitride-based material, or diamond. The semiconductor element formed of such a wide bandgap semiconductor can be miniaturized because of high withstand voltage and high allowable current density. By using this miniaturized semiconductor element, the semiconductor device in which the semiconductor element is assembled can also be miniaturized and highly integrated. In addition, because of high heat resistance of the semiconductor element, the heat dissipation fins of the heat sink can be miniaturized, and the water cooling portion can be air-cooled, and thus the semiconductor device can be further miniaturized. In addition, because of low power loss and high efficiency of the semiconductor element, the semiconductor device can be made efficient.

[0053] In addition, the semiconductor element 8 constituted of a wide bandgap semiconductor can achieve high-temperature operation. In contrast, the stress to the solder 14 can be reduced by applying the above-described embodiments, and thus the reliability at high temperature is improved.

[0054] Explanation of Reference Signs

[0055] 1insulating substrate, 4circuit pattern, 6base plate, 8semiconductor element, 10wiring, 11housing, 11aouter wall, 11bprotruding portion, 12electrode, 12afixed portion, 12erising portion, 12dpin, 12ecutout, 14solder, 15encapsulating material, 16recess

Claims

1. A semiconductor device, characterized in that, have: An insulating substrate having a circuit pattern; A semiconductor element, which is mounted on the insulating substrate and electrically connected to the circuit pattern; A housing that houses the insulating substrate and the semiconductor element; as well as Electrodes, which are disposed in the housing, The front end face of the electrode is soldered to the circuit pattern using solder. The electrode is pressed onto the circuit pattern by the housing. A protrusion is provided on the front end face. The electrode has a fixing part that is fixed to the housing and an erecting part that stands upright on the circuit pattern. The height of the upper end of the raised portion of the electrode is higher than the height of the fixed portion.

2. A semiconductor device, characterized in that, have: An insulating substrate having a circuit pattern; A semiconductor element, which is mounted on the insulating substrate and electrically connected to the circuit pattern; A housing that houses the insulating substrate and the semiconductor element; as well as Electrodes, which are disposed in the housing, The front end face of the electrode is soldered to the circuit pattern using solder. The electrode is pressed onto the circuit pattern by the housing. A protrusion is provided on the front end face. The housing has an outer wall that surrounds the insulating substrate and the semiconductor element, and a protrusion that extends from the outer wall to the inside of the outer wall. The electrode is pressed down by contacting the lower surface of the protrusion, thereby receiving a force that presses it against the circuit pattern.

3. The semiconductor device according to claim 1 or 2, characterized in that, It also has a base plate, The insulating substrate is bonded to the upper surface of the base plate. The housing is bonded to the upper surface of the base plate.

4. The semiconductor device according to claim 1 or 2, characterized in that, The housing is directly bonded to the insulating substrate.

5. The semiconductor device according to claim 1 or 2, characterized in that, The circuit pattern has recesses. The protrusion is fitted into the recess.

6. The semiconductor device according to claim 1 or 2, characterized in that, It also has other electrodes arranged in parallel with the said electrodes.

7. The semiconductor device according to claim 1 or 2, characterized in that, The protrusion is not located on the outer periphery of the front end face.

8. The semiconductor device according to claim 1 or 2, characterized in that, A cut is provided on the side of the raised portion of the electrode.

9. The semiconductor device according to claim 1 or 2, characterized in that, The thickness of the raised portion of the electrode is locally reduced.

10. The semiconductor device according to claim 1 or 2, characterized in that, The semiconductor element or wiring is attached to the circuit pattern on which the electrodes are attached.

11. The semiconductor device according to claim 10, characterized in that, The distance from the junction of the electrode and the circuit pattern to the end of the circuit pattern, the semiconductor element, or the wiring is greater than or equal to the height of the solder.

12. The semiconductor device according to claim 1 or 2, characterized in that, It also includes a resin that encapsulates the insulating substrate, the semiconductor element, and the electrode.

13. The semiconductor device according to claim 1 or 2, characterized in that, The semiconductor element is formed from a wide-bandgap semiconductor.

14. A method for manufacturing a semiconductor device, wherein the semiconductor device is the semiconductor device according to any one of claims 1 to 13. It is characterized by having the following processes: Semiconductor components are mounted on an insulating substrate and electrically connected to a circuit pattern on the insulating substrate; and The housing is mounted in a manner that accommodates the insulating substrate and the semiconductor element, and the front end faces of the electrodes disposed on the housing are soldered to the circuit pattern. During the installation of the housing, the electrodes are pressed onto the circuit pattern through the housing. A protrusion is provided on the front end face.

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